240, Exhaust rattles and Lambda error code

cobalt60 · Post by **cobalt60** » 18 Sep 2016, 09:48

My car is a 1991 Volvo 240 with manual transmission. I just moved into a state that will require me to pass emissions (Connecticut). My check engine light comes on, and when I read the error code, it says Lambda sensor, which I believe is just another name for the Oxygen sensor. If I reset the light by unplugging the battery, the check engine light will come back on soon, though not necessarily immediately. The exhaust is new behind the Catalytic Converter, but the Cat itself is probably original. I hear a loud rattle at about the same rpm, so can happen in a parking lot or on the highway, and it will continuously rattle if I maintain the same rpm.

So, I am thinking these are symptoms of a bad Cat. If that is the case, how can I get one as inexpensively as possible? I just want to pass emissions. I see universal Cats on eBay for around $50; will those work? Or should I look into something different. For $50, I do not mind if these Cats only last 2 years.

Thanks for any help with this

93Regina · Post by **93Regina** » 18 Sep 2016, 11:16

cobalt60 wrote:1991 Volvo 240

Not uncommon to buy and install OEM type plugs, cap, rotor, along with O2 sensor, before an emission test. If vehicle has an older wire set, then getting a new Bougicord Ignition Wire Set (OEM) is best...some $50.00 if you look around.

If head has been shaved down too much, or other engine rebuilt modifications, there might be an issue with a smog test.

A higher weight oil might be considered, if engine is burning some oil.

cobalt60 · Post by **cobalt60** » 18 Sep 2016, 11:45

Not uncommon to buy and install OEM type plugs, cap, rotor, ... before an emission test.

Oh good, pretty sure I need those anyway since the car is difficult to start after rain / high humidity.

Post by **kcodyjr** » 27 Sep 2016, 14:09

Difficulty starting due to moisture does point to an ignition problem, more likely with the high voltage side.

Re: exhaust rattle at a particular RPM. Is it a loose heat shield?

I suppose a loose piece of crap inside the cat is also possible. Remember that exhausts rust from the inside out, and yours cat-forward is old enough to run for public office.